Nissan Pino CAT and high HC emissions

Hey all,

I have a 2007 Pino, and am getting concerned about high HC emissions which I found out from one of the ENERCON test centers in G-10. I guess it was around 480-490. Two months ago I had my CAT cleaned and half removed because it was choked, and car performance was great for some time. But now it's choked again, the acceleration and power is pathetic, and there is high HC emission.

What do you suggest? As a first step I am going to get a new set of iridium plugs, although previous ones were also iridium and lasted only 1 year. Is the CAT dead? Or is there something wrong with sensor/engine/valve? Guy at ENERCON comupter testing said that the tappets were "too tight", but he just said that by looking at computer results.

Your expert suggestions are welcome please. First preference would be to not remove the CAT.